VulnerabilityPublished 18 Oct 2026

CVE-2026-98818: Linux kernel · mm/slab: do not wake up kswapd in __kfree_rcu_sheaf()

Source GCVE Database

Authoritative record:CVE-2026-98818· High

Not known to be exploited : upgrade to af2fb3ee6679b517e2fdbd3ba16ec276a8b74312 or 46545c86b54ffb969b6e3662942b4a6191619eaa soon.

Data as of 26 Oct 2026, 14:05 UTC

Severity

High

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in af2fb3ee6679b517e2fdbd3ba16ec276a8b74312, 46545c86b54ffb969b6e3662942b4a6191619eaa

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-hqwf-4r5g-q2h4

What to do

Upgrade Linux kernel to af2fb3ee6679b517e2fdbd3ba16ec276a8b74312 or 46545c86b54ffb969b6e3662942b4a6191619eaa.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ ec66e0d599520ab414db745544e25d80d0ac5054, < af2fb3ee6679b517e2fdbd3ba16ec276a8b74312	Fixed in af2fb3ee6679b517e2fdbd3ba16ec276a8b74312
LinuxLinux	Affected ≥ ec66e0d599520ab414db745544e25d80d0ac5054, < 46545c86b54ffb969b6e3662942b4a6191619eaa	Fixed in 46545c86b54ffb969b6e3662942b4a6191619eaa
LinuxLinux	Affected =6.18	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to prevent kfree_rcu() from waking kswapd under pi_lock, thereby avoiding the deadlock. Users should apply the official kernel updates that include this fix. Since this is a kernel-level issue, updating to a patched kernel version is the recommended remediation.

Description

A deadlock vulnerability in the Linux kernel's memory management subsystem was resolved. The issue involved the function __kfree_rcu_sheaf() waking up kswapd while holding a raw spinlock (pi_lock), which could lead to a circular locking dependency and deadlock. This deadlock was difficult to reproduce and was verified using a modified kernel with lock dependency detection. The vulnerability was fixed by ensuring kfree_rcu() does not wake up kswapd under pi_lock.

Impact

The vulnerability could cause a kernel deadlock, potentially freezing affected systems or kernel threads. However, reproducing the deadlock was not straightforward and required specific conditions. There is no indication of direct security compromise such as privilege escalation or data corruption, but system stability could be affected.

Summary

The Linux kernel vulnerability CVE-2026-98818 concerns a deadlock caused by __kfree_rcu_sheaf() waking up the kswapd kernel thread while holding the pi_lock raw spinlock. Since kfree_rcu() can be called under pi_lock, waking up kswapd (which also acquires pi_lock) leads to a circular locking dependency and deadlock. The issue was confirmed using a kernel with lockdep instrumentation, revealing a complex lock dependency chain involving pi_lock and kswapd_wait. The fix prevents kfree_rcu() from waking kswapd under pi_lock, eliminating the deadlock scenario.

References

Community reviews

Loading reviews…